Post your favorite "feel good" song. The one song that's guaranteed to reverse your bad mood.

I was driving this morning in a foul nasty mood just itching for some idiot to tailgate me, and this song came on the radio. Changed my mood completely. Post your feel good singalong song so we can all be in a good Sunday mood.
[youtube=https://www.youtube.com/watch?v=IK1chmK5BGQ]